1. Field of the Invention
The present invention generally relates to multibeam recording/reproducing apparatuses, and more particularly, to a multibeam recording/reproducing apparatus recording/reproducing information by irradiating an optical recording medium with a plurality of light beams.
2. Description of the Background Art
In an optical recording medium driving device disclosed in Japanese Patent Laying-Open No. 5-12677 and an optical disk driving device disclosed in Japanese Patent Laying-Open No. 64-60823, reflected light of a single light beam is converted into an electrical signal by a two-divided detector to generate a sum signal and a difference signal. Based on the phase relationship between the two signals, the direction of movement of light beams is determined.
An optical memory device disclosed in Japanese Patent Laying-Open No. 59-185044 is a multibeam recording/reproducing apparatus irradiating an optical recording medium with a plurality of light beams, wherein tracking control is carried out by one of the plurality of light beams, and information is recorded/reproduced by the other light beams.
In the former apparatus using a two-divided detector, an adder and a subtractor for generating a sum signal and a difference signal, respectively, are required in order to determine the crossing direction of light beams, preventing simplification of the apparatus. The same problem occurs when the concept of the apparatus is applied to the above multibeam recording/reproducing apparatus. There is a need to have a method of determining the direction of movement of light beams suitable for the multibeam recording/reproducing apparatus.